Wireless Power Transmitter Slot Timing for Foreign Object Detection
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Solution Overview
Problem
Existing wireless power transfer systems face challenges in accurately measuring the quality factor (Q factor) and detecting foreign objects between the transmitter and receiver.
Innovation Solution
A wireless power transmitter is designed to temporarily stop wireless power transmission during a slot time, allowing for the detection of foreign objects by analyzing changes in voltage or current of the primary coil, and more accurately measuring the Q factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wireless power transmission is continuously performed, then power transfer efficiency is maintained, but foreign object detection accuracy deteriorates
Solution Approach 1:
The patent implements periodic action by temporarily suspending wireless power transmission at specific intervals (slot times) to perform foreign object detection. The system alternates between power transmission mode and detection mode, allowing accurate measurement of Q factor and detection of foreign objects while maintaining overall power transfer functionality. This periodic interruption resolves the contradiction by enabling detection without completely stopping power transfer operations.
2Measurement precision
If Q factor measurement is performed during active transmission, then measurement speed is improved, but measurement precision deteriorates
Solution Approach 1:
The patent applies preliminary action by performing foreign object detection during the idle period before the next power transmission cycle begins. The slot time for detection is strategically positioned at the boundary between transmission cycles, allowing the system to complete measurements before power transmission resumes. This ensures accurate Q factor measurement without significantly extending the overall operational cycle.
3Reliability
If slot time for detection is extended, then detection accuracy is improved, but power transmission efficiency deteriorates
Solution Approach 1:
The patent implements partial action by performing foreign object detection using only a portion of the available idle time between transmission cycles. Rather than extending detection into the active transmission period, the system utilizes the existing slot time efficiently, achieving sufficient detection reliability without compromising power transmission efficiency. The detection process is optimized to complete within the allocated slot time window.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables more accurate detection of foreign objects and measurement of the Q factor, improving the reliability and efficiency of wireless power transfer systems.
Implementation Method 1
The magnetic induction method corresponds to a method transmitting power by using electric currents that are induced to the coil of the receiver by a magnetic field, which is generated from a coil battery cell of the transmitter, in accordance with an electromagnetic coupling between a transmitting coil and a receiving coil.
Implementation Method 2
a method of transferring power by using radio frequency (RF)
Data Source
AI summary
A wireless power transmitting device according to an embodiment of the present specification transmits wireless power to a wireless power receiving device, and includes a power conversion circuit including a primary coil for transmitting the wireless power to the wireless power receiving device and a communication/control circuit for communicating with the wireless power receiving device and controlling the power conversion circuit, wherein, to detect foreign substances between the wireless power receiving device and the wireless power transmitting device, the communication/control circuit stops the transmission of the wireless power for a slot time, detects the foreign substances on the basis of a change in the voltage or current of the primary coil within the slot time, and sets the slot time to start from a point in time when the current of the primary coil is 0.